Research

In April 2011, for the first time in Britain, the relevant professional bodies concerned with trees and the built environment came together to hold a major international research conference hosted by the Institute of Chartered Foresters and titled Trees, People and the Built Environment (TPBE). A second conference, Trees, People and the Built Environment II (TPBEII) was held at the University of Birmingham in April 2014. A weblink to download the proceedings of each of these events can be found on our ﻿External resources﻿ page.

As a follow-up to the first TPBE conference TDAG set up a working party focusing on research investigating the natural and built environment issues that ought to be better understood for effective decisions on urban trees. The research working party focuses on identifying:

Published research papers that have relevance

Current research projects

Gaps in research that needs to be filled

These activities help ensure that the TDAG Guides are based on the most up-to-date research findings. Regular updates from the TDAG research working party are circulated to TDAG members via forum meetings and associated meeting minutes.

These activities have also given rise to research projects:

In June 2014, TDAG received a Fund4Trees research grant to explore “What we know and don’t know about the physical benefits of urban trees”. This work focused specifically on the cooling, stormwater attenuation and carbon sequestration benefits of urban trees. Findings are available below.

In March 2016, Myerscough College, Lancaster University and TDAG were awarded a NERC grant to conduct some research on "Tree species for green infrastructure". As further detailed below, the end-goal of this project is to provide the basis for the development of new guidance by TDAG.

TDAG is currently developing a proposal to explore “What we know and don’t know about the public health and social value of trees”.

1. What we know and don’t know about the cooling, stormwater attenuation and carbon sequestration benefits of urban trees

Some considerable research has been and continues to be carried out on the physical benefits of urban trees in the UK, the rest of Europe and beyond. However, initial surveys of the literature suggest that, while some areas have already been well covered, the work has been carried out by many isolated groups of researchers and consequently there has been no overall methodological framework, or even consistent physical basis for their investigations. In addition, some of the benefits have only been modelled, not investigated by experiment, while in many other cases only generic benefits of “typical” trees have been quantified with little investigation of the influence of tree species or cultivation techniques. The result is that, while there is good deal of literature, it is often quite inaccessible to practitioners and the general public.

Conducted Dr. Mohammad Rahman from the Technical University of Munich and Prof. Roland Ennos from University of Hull thanks to a £5,000 Fund4Trees research grant, this project aimed to collect and review the research that has been carried out on the physical benefits of urban trees, identify what is and what is not known about them, and how best to improve our knowledge. The list of physical benefits delivered by trees in the urban environment being quite long, the research scope was narrowed to the following three areas of physical benefits which are often used as a basis for decision-making on urban greening policies and pursued through landscape design in individual projects:

Stormwater attenuation – This article published in the The Conversation on 10 December 2015 provides an overview of findings. Full details can be found in the paper available for download below.

Temperature cooling – This article published in The Conversation on 22 December 2015 provides an overview of findings. Full details can be found in the paper available for download below.

Carbon sequestration – Findings are detailed in the paper available for download below.

Research Paper: What is known and not know about the stormwater attenuation benefits of urban trees.pdf

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Research Paper: What is known and not know about the cooling benefits of urban trees.pdf

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Research Paper: What is known and not know about the carbon sequestration benefits of urban trees.pdf

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2. Tree species selection for urban green infrastructure

All those involved with establishing trees in the urban landscape will appreciate the importance of selecting the right tree for planting projects. With the challenges of a changing climate and the challenging nature of many urban planting sites, selecting appropriate plant material has never been so important. We must plant trees capable of thriving, not just surviving. This must also be done using a diverse range of tree species so that our critical green infrastructure is resilient to the known, and unknown, threats of the future.

Myerscough College, Lancaster University and TDAG were awarded in March 2016 NERC research grant to explore approaches to tree species tree selection for urban green infrastructure. Knowledge exchange is central to the objectives and methodology adopted for this work. Therefore, there will be lots of opportunities to contribute to the outcomes of the project. The first of these will be in the form of a survey of current selection practices. To take part in this survey, please follow this link: https://www.surveymonkey.co.uk/r/Tree-Selection (will remain open until 3rd June 2016). ​There will also be an opportunity for a team from Myerscough College and Lancaster University to evaluate a wide range of species for their leaf turgor loss point, a key trait associated with drought tolerance. These data, along with information from a wide range of published literature and the experience of practitioners will then be used to develop some TDAG guidance on tree selection. It is hoped that this will be a valuable decision making tool for you to use when making tree selection decisions.

Publication of this guidance will be followed by a series of knowledge exchange seminars outlining the project findings in the autumn of 2017. We’ll obviously keep you informed about these events.

This exciting project is still in its infancy so if you would like to know more about it or if you are willing to share you experience of tree selection, then please do get in touch with Andrew Hirons (ahirons@myerscough.ac.uk).

3. What we know and don’t know about the public health and social value of trees

Following its work some of the physical benefits associated with urban trees (see point 1. above), TDAG is currently working with subject-expert Prof. Kathleen Wolf from University of Washington, Oregon, on developing a proposal to explore what is and what is not known about the public health and social value of trees. If you would like to know more about this proposal or take part in its development and implementation, feel free to contact Sue James (suejamesriba@gmail.com).